, the fbi says a letter sent to presidentbarackobamahastested positive for the deadly poison ricin. >> the letter was intercepted tuesday at a mail screening facility. american media say that the letter sent to obama and another letter sent to roger wicker were both postmarked memphis, tennessee. additional tests are due in the next 48 hours to confirm the presence of the toxin. >> our washington correspondent is following this for us. any idea as to who might be behind this? >> oh -- we do not have a suspect yet, but there was a signature on the letters. the letters included the phrase "to see a wrong and not to expose it is to become to -- a silence -- is to become a silent partner to it." president obama said, "i am president obama and i approve this message." this is someone who wants to get attention. it is important to note that both are getting letters right now, republicans and democrats. that says to me this is someone who really hates government. the u.s. -- in the u.s., antigovernment extremists have a fascination with ricin in the past. you can easily buy manuals on how

to presidentbarackobamatestedpositive for the poisonous ricin. the u.s. secret service said the letter was intercepted as a white house mail screening facility on tuesday. press secretary jay carney says the president has been briefed on the letter and orders the investigation continue in the boston bombings first and say this is no indicated link between the letters and the bombing bombings. >> . >> the bombings in boston that killed and maimed people have his absolute focus. >> u.s. media say a suspicious letter was also found at the congressional office of republican senator richard shelby of alabama. and senator roger wicker was also targeted this week. >>> chinese warships patrolled disputes islands wednesday as part of an exercise. the senkaku islands are controlled by japan but claimed by china and taiwan. china's state-run media say the ships are part of their navy fleets, including a missile destroyer and a missile frigate. the vessels entered the waters on tuesday night and stayed until just before dawn the next day, after conducting drills in the western pacific. they practi